I just matched at Carolinas and rotated there last fall. It is definitely true that they don't offer everyone who rotates there an interview, which can be tough if you've busted your butt there for a month. I really enjoyed my rotation and have no doubt that working with the residents and attednings significantly improved my chances to match there.
In general, I think rotating helps you at most places if you do well. If you don't do well, then you've obviosuly shot yourself in the foot. It is a gamble, but one that is worth it most of the time in my opinion.
If you want to match in a specific program, then my advice is to rotate there. You'll get a better feel for things and get to know the residents and faculty in much better detail. Remember, an away rotation is as much about YOU deciding if you like the place as them deciding if they like you. However, you should also be realistic and know that some places are very competative even if you rotate there AND do very well.
If you want to match in a region (southeast, midwes, California, etc), then picking a program in the same region definitely helps. If you're not dead-set on a specific program, pick the best student rotation and location where you think you can get the best letter. I also think there is something to be said for rotating at a program that is a different type than your own home program, for example going to a county program if you're from a very academic place, etc.
Off the top of my head, I've heard great things about the student rotations at Indy, Vandy, and Emory. I also rotated at UNC and Carolinas, which I thought were excellent months as well. I'm sure others can chime in and give other examples of great student rotations at other programs and in other areas of the country.